Torsional behavior of chiral single-walled carbon nanotubes is loading direction dependent

The torsion of carbon nanotubes is studied by molecular dynamics simulations. The torsional behavior of a chiral single-walled carbon nanotube (SWCNT) is dependent on the loading directions due to its structural asymmetry. The critical buckling shear strain of a SWCNT in one direction may be 1.8 times higher than that in the opposite direction. This means that one can choose the most appropriate SWCNT for his special purpose in designing a torsional component (e.g., oscillators and springs) of nanomechanical devices using carbon nanotubes. Meanwhile, the finding indicates that a simple thin shell model is not suitable for predicting torsional behavior of small SWCNTs at large strains. (C) 2007 American Institute of Physics.